What trouble shooting measures have you tried?
- have you upgraded to the latest Aperture version?
- Have you repaired/rebuild both libraries in question? Repairing and Rebuilding Your Aperture Library: Aperture 3 User Manual
- Have you tried to import into a new, empty library?
- Does the library contain PhotoStream images?
- Can you merge libraries, when working from a different user account?
- Look at this article, for any trouble shooting measure you have not tried already: Aperture 3: Troubleshooting Basics
Thanks, Leonie. Yes - I had done all those things!
After many hours of frustration I did manage to solve it as follows - maybe useful for someone else. Clearly this is an Aperture bug and disgraceful that Apple does nothing about it for so long.
I copied the "to be imported library" to my main computer
I experted a small projecct as a libarary from main library
Switched to the "to be imported" library and imported the small library - for some reason that worked!
Switch back to the main library
Import the "to be imported library".... this time I get the dialog box and click ADD
The import goes OK but the small project is now duplicated.... just delete the one with (1) on the end
Thanks for your suggestions!
This is something that worked for me.
If you have Aperture 3 and iPhoto '11 installed in the same machine, open the main library (to receive the imports) in Aperture and keep it open in the Projects window.
Then open a library (.aplibrary) with the projects you want to import into the main library, but with iPhoto.
In iPhoto, Aperture Projects are Named Events. In the Events window of the iPhoto, click on the Event (Project) to be imported, and drag into the Aperture Icon on the Dock on your screen. (DO NOT drag into the Aperture Projects window that nothing will happen.)
The dragged Event will show up as a new Untitled Project in the Aperture Projects window.
That's it. In my case I work usually with self-contained Aperture Libraries. But there's no reason it shouldn't work with libraries using referenced masters.
Considering that -- for all I know -- you can't have two sessions/libraries open in Aperture at the same time, I've been solving some problems in my workflow using iPhoto and Aperture open at the same time in my iMac.
Same problem; here's my workaround. (1) open "new small library" I want to merge into "old large main library". Aperture opens with this one project in the small new library. (2) export project as library, naming it "small new library copy". (3) switch to "old large main library". (4) import "small new library copy", producing add/merge choice. After clicking add, it works. Tiresome, but it works.